Carrier transmission system for printing telegraphy



Jan. 14, 1930. H. A. AFFEL ETAL CARRIER TRANSMISSION SYSTEM FOR PRINTING TELEGRAPHY 3 Sheets-Sheet 1 I Original Filed Aug .'29, 1919 @EPHZMZJZZZIZ/ 14,-1930- H. A. AFFEL ETAL 1,743,588

CARRIER TRANSMISSION SYSTEM FOR PRINTING TELEGRAPHY Original Filed Aug. 29, 1919 3 Sheets-Sheet 2 K 4/ INVENTOR ATTORNEY Jan. 14, 1930. H. A. AFFEL ET AL CARRIER TRANSMISSION SYSTEM FOR PRINTING TELEGRAPHY S Sheets-Sheet 3 Original Filed Aug. 29, 1919 k ATTORNEY Patented Jan. 14, 1930 UNITED STATES PATENT OFFICE HERMAN A. AFFEL AND BAXTER P. HAMILTON, OF BROOKLYN, NEW YORK, ASSIGNORS TO AMERICAN TELEPHONE & TELEGRAPH COMPANY, A CORPORATION OF NEW YORK CARRIER TRANSMISSION SYSTEM FOR PRINTING TELEGRAPHY Application filed August 29, 1919, Serial No. 320,667. Renewed November 25, 1929.

This invention relates to multi plex transmission and more particularly/to multiplex systems .in which carrier currents are employed for the transmission of signals.

Multiplex transmission by means of carrier currents is accomplished by superimposing upon a transmission circuit such as a wireless antenna, or an ordinary wire transm ssion line, such as a telephone or telegraph, line, a plurality of carrier currents of different frequencies, said carrier currents being used for the selective transmission of telephone or telegraph signals by imposing thereon by modulation or otherwise the low frequency currents representing the signal to be transmitted.

It is one of the objects of this invention to adapt a multiplex'system of this character to the transmission of printing telegraph messages. A further object of the invention has reference to further increasing the capacity of a multiplex carrier system by utilizing each channel for the transmission of a plurality of printing telegraph messages.

These objects, as Well as other ob ects more fully hereinafter appearing may be accom plished by associating with each transmitting channel of a carrier system means for translating low frequency impulses into carrier oscillations, and by providing transmitting apparatus including the distributor of a printing telegraph arrangement, said apparatus being so arranged as to transmit to the translating apparatus code comblnatlons of impulses corresponding to characters to be printed. For receiving purposes each channel is provided with means for translating carrier oscillations into corresponding code combinations of low frequency impulses whichin turn are transmitted through a distributor to a receiving printer.

\Vhere printing apparatus, such as the socalled start-stop printer, is to be used, one printing channel will ordinarily be associated with each carrier channel. A eater number of printing channels may, however,

"be associated with each carrier channel,

especially where printers of the multiplex type are employed. I-nthis case at the sending station a distributor will be provided for .sion line ML is illustrated, which line may each carrier channel having associated therewith a plurality-of code transmitters, the dis tributor operating to successively transmit to the carrier. translating means successive codecombinations of impulses from the several transmitters. Similarly, for receiving purposes, a distributor Will be provided having acorresponding plurality of printing means associated therewith, said distributor functioning to transmit to the corresponding printers successive groups of impulses corresponding to code combinations.

The invention may now be more fully understood by reference to the following descrlption when read in connection with the accompanying drawings, Figures 1 and 2 of which when taken together constitute a simplified diagram of an embodiment of the invention employing one printer channel for each carrier channel, while Figure 3 constitutes a simplified diagram of a system in which a plurality of printing channels may be associated with each carrier channel.

Referring to Figures 1 and 2, a transmisbe an ordinary wire telephone line, termi nating in a terminal telephone circuit LT. In order that the line may be employed for multiplex carrier transmission a carrier branch CB is'provided, said branch having included therein a high pass filter HF, for the purpose of excluding low frequency signaling currents. A. low pass filter LF is included between the mainline ML and the low frequency terminal circuit LT, for the purpose of excluding from the low frequency circuit 'high frequency carrier oscillations. The

filters HF and LF are of the general type, illustrated and described in United States patents to George A. Campbell Nos. 1,227,113 and 1,227 ,114, dated May 22, 1917. The filter LF is designed in accordance with the principles of said Campbell patents so as to freely transmit a band of frequencies extending from zero to the upper limit of frequencies employed'in ordinar telephonic transmission, while substantially suppressing fre quencies above said upper limit. Conversely, the filter HF is designed to freely transmit frequencies above the upper limit employed in ordina telephonic .transmission while substanti y suppressing frequencies below said limit.

The carrier branch GB is associated with acommon transmitting circuit TL and a common receiving circuit RL, throu h a balanced transformer arrangement 10, avin associated therewith an artificial M to balance the apparatus on the main line side of the transformer so that the circuits TL andthrough selecting circuits which in this case are illustrated as sharply tuned circuits TF TF TF TF etc. In a similar manner the receiving circuit RL isassociated with a plu-, rality ofjreceiving channels through selecting circuits which are also illustrated as sharply tuned. RF1, RF=, RFQ, RF4, etc. 7 In the drawing the transmitting and receiving carrier apparatus for one transmitting and receiving channel only is illustrated. The transmitting apparatus comprises a vacuum bulb oscillator Gr adapted to generate high frequency oscillations of the freuency assigned to the corresponding carrier 0 annel. An amplifier TA is provided between the oscillator Gr and thetuned circuit arrangement TF in order to amplify the generated oscillations. The circuit of the oscillator G, is controllled by l: relay 20 tcontrolled b the rintin te e transmit ing appard tus h reinaft er The corresponding apparatus of the receiving channel comprises vacuum bulb amplifiers RA and RA, and a vacuum bulb detector D in the output circuit of which is a direct current relay*21 for transmitting to the receiving printer apparatus hereinafterdescribed, the low fre: quency impulses corresponding to the code combinations arising at the sending station.

The transmitting relay 20 is under the control of the transmitting apparatus illustrated in Figure 1 which comprises a start-stop distributor TD for transmitting to the relay 20 code combinations of impulses corresponding to, a character to be printed. The code combinations may be set u either by a tape transmitter schematically indicated at TT, or by a keyboard transmitter schematically indicated at KT., Gang switch S is provided for shifting the distributor circuits to either the tape transmitter or the keyboard transmitter.

The receiving printer apparatus controlled the receiving relay 21 comprises a receiving distributor RD of the start-stop type for transmitting the code combinations of 1mpulses received by the relay 21 a corresponding receiving printer RP which may be of any well-known character. Since the details of the printer constitute no part of the 1,74a,saa

present invention, said element is merely inure 1, the transmitting apparatus is under the control of the tape transmitter and assuming that a suflicient amount of tape has been perforated to permit the tape lever 22 to be closed a circuit is completed as follows:

From grounded segment 23 of the inner ring of the distributor TD, brush arm 24, re-

leasing pawl 25 of the starting magnet. SM,

conductor 26, eight-h contact of, the gang switch,'tape lever 22, conductor 27, upper 'winding of starting relay STR to battery.

Start-ing relay STR upon being energized Y completes a locking circuit from ground.

through its lower winding, over its lower front contact and over the upper'back-contact of stop relay SPRto battery.

The transmitting relay 20 is in a normally closed circuit which is under the joint control to be transmitted. 'The first or starting impulse is for the purpose of setting the receiving distributor intooperation and always corresponds to an open circuit condition The next five impluses may correspond to either open or closed circuit conditions in any order and determine the character to be printed.

The seventh impulse is always a closed circuit impulse and is for the purpose of stopping the apparatus or restoring it to normal.

The start relay STR upon being energized as above described opens the circuit of the relay 20, thereby transmitting .the starting impulse. At the same time a-circuit for the starting magnet SM is completed from battery over' the upper back cont-act of relay SPR, lower front contact of relay STR, through thewinding of magnet SM, over the starting segment S, brush arm 24 to grounded segment 23 of the inner ring of the distributor. releases the brush arm 24 which now rotates over the various segments of the distributor.

As soon as the brush arm 24 passes from the starting segment S the starting magnet SM is de-energized so that its releasing pawl 25 is ready to engage the brush arm at the end of Starting magnet SM is energized and 20 is now determined by the segments 0 outer ring of the distributor and theare shifted from the bus-bar 28 to the live bus-bar 29. As the brush arm 2& passes over the first segment of the outer ring of the distributor TD, a closed circuit impulse will be transmitted to the relay from battery over the segment 30 of the inner ring of the distributor, brush arm 24, first segment of the outer ring, through the winding of the first home recorder relay, over the first contact of the gang switch, first contact of the tape transmitter TT, bus'bar 29 and through the winding of relay 20 to battery. The first character determining impulse thus transmitted to the relay 20 is therefore a closed eir cuit impulse. I

The brush arm now passes to the second segment of the distributor which 1s con- .nected through the second home recorder relay and the second contact of the gang switch to the second contact of the tape transmitter. Since the second contact of the tape transmitter is not shifted into contact with the bus-bar 29, the circuit of the relay 20 is not closed and the second code forming impulse corresponds to an open circuit condition.

. As the brush arm passes to the third seg' ment of the distributor a circuit for relay 20 is completed over the brush arm from the segment 30 of the inner ring to the third segment of the outer ring, through the wlnding of the third home recorder relay, third contact of the gang switch, third contact of the tape transmitter and over bus-bar 29 to the relay 20. The third character determining impulse is therefore a closed circuit impulse.

In a similar manner, as the brush arm passes over the fourth and fifth segments of the distributor, an open circuit condition followed by a closed circuit im ulseis transmitted to the relay 20. The fth home recorder relay is at the same time actuated.

The brush arm upon passing to the sixth segment of the distributor closes a circuit from grounded segment 23, over the brush arm 24:, sixth segment of the outer ring of the distributor, through the winding of stop relay SPR to battery. At its upper contact stop relay SPR opens the locking circuit of the start relay STR which is accordingly deenergized and at its upper back contact closes the circuit of relay 20 to transmit the final closed circuit impulse of the series. At its lower front contact stop relay SPR closes a circuit from battery, over the conductor 30, through the sixth home recorder relay, sixth contact of the gang switch S, over conductor 31 and through the winding of the tape transmitter magnet 32 to ground. The tape transmitter magnet operates in a well-known manner to move .the tape forward and set up a new combination upon the transmitter. The sixth home recorder relay closes a printing 1 circuit leading to the home printer (not shown) to print the character determined by the operation of the first, third and fiftl home recorder relays in a well understood. manner.

The brush arm 24 now passes to the start segment S of the distributor andcomes .to rest in engagement with the releasing pawl 25. If the tape lever 22 is still closed, the starting circuit ori inally described is completed over the brus 1 arm 2% and the pawl 25 so that the distributor is again released and operates to transmit the succeeding combination of impulses. t I

When the keyboard transmitter is used for determining the code combinations to be transmitted, the operation is slightly different from that above described. In this instance,

the gangswitch is shifted to its alternative position, thereby shifting the connections of the code segments of the distributor from the tape transmitter TT to the keyboard transmitter KT.

Assumingithat in the operation of a given key of the keyboard the first, third and fifth of the keyboard selecting contacts are closed and that at the same time the common keyboard contact 33 (which is actuated each time a key is depressed) is'closed, a circuit is completed from ground, over contact 33, conductor 34, seventh contact of the gang switch S, conductor 35, winding of overlap relay OR, lower back contact of keyboard relay KBR, left hand back contact "of lockout relay LOR, and thence in parallel over the first, third and fifth keyboard contacts through the upper windings of the first, third and fifth keyboard selecting relays, to battery. third and fifth keyboard selecting relays are actuated over the circuit above traced, the keyboard selecting relays completing locking circuits from battery, through their lower windings, over their lower front contacts, through the windingof relay KBR, and over the right hand back contact of relay LOR to ground. The relay KBR is now energized and at its lower contact opens the initial energizing circuit for the keyboard selecting relays. These selecting relays being now locked up, store the core combination set up The overlap relay OR and the first,

by the keyboard selecting contacts and thfese contacts may be actuated to set up a different combination without disturbing the combination previously set up.

The overlap relay OR upon being energized, completed a locking circuit from battery, over its upper front contact, through its winding, over conductor 35, seventh contact, of the gang switch, conductor 34 and over common keyboard contact 33 to ground.

The overlap relay therefore remains locked up so long as the key which has just been depressed is held down. Relay KBR upon being energized, completes the starting circuit for the transmitting distributor TD from brush arm passes over the first se ment of the outer ring of the distributor, a c osed circuit impulse is transmitted to the relay 20 determining impulses.

over a circuit from batter segment 30, brush arm 24, first segment 0 theouter ring of' Y the distributor, first home recorded relay,

first contact of the gang switch in its alternate position, upper front contact of the first keyboard selecting relay, conductor 37, through the winding of transmitting relay 20, to battery. This impulse constitutes the first impulse of the group-of five character As the brush arm continues its rotation, 'similar circuits are com leted over the third and fifth. segments of t e outer ring of the distributor and the upper front contacts of the th'rd and fifth keyboard selecting relays, thereb energizing the third and fifth home recorder relays in addition to the first home recorder relay and transmittin closed circuit impulses to the relay 20.. pen circuit conditions occur as the brush passes over the second and fourth segments.

As the brush passes over the sixth segment of the distributor, a circuit previously described is com letedfor the stop relay SPR 'which opens tiie locking circuit of the relay STR, thereb transmitting the final closed circuit'impu se to the relay 20. The relay SPR over its lower front contacts completes a circuit from battery, over the conductor 30, through the winding of the sixth home recorder relay, sixth contact of the gang switch in its alternate position, and over theconductor 38, through the left hand winding of the lockout relay LOR, to ground. The sixth home recorder relay closes a printing circuit for the home printer so that the combination determined by the-actuation of the first, third and fifth home recorder relays is printed in a well known manner.

The lockout relay LOR at its left hand' contact opens at another point the initial energizing circuit for the keyboard selecting relays which, it will be remembered, was traced over the,actuated keyboard selecting contacts. At its ri ht hand contact, relay LOR opens the loc 'ng circuit of the keya board selecting relays which are'restored to normal. The operation from this point depends on whether or not the operator has held down the key originally actuated or whether it has been released before the lockout relay LOR was actuated. If the key is the circuit of the keyboard rela still depressed, the common keyboard contact 33 still remains closed and the overlap relay OR will, therefore, still remain .locked up. Consequently when the lookout relay LOR is energized, a lockin circuit'is closed from through the right hand winding of relay LOR, and over the lower contact of the overlap relay OR to battery. The lockout relay If, on the other hand, the operator had. I

already restored the key, the common keyboard contact would have opened, thereby deenergizing the overlap relay OR so that the lockout relay would not be locked up but would simply operate momentarily to open and the locking circuit of the keyboard se ecting relays. If, in the meantime, the operator had again actuated either the same key or another key to set up a new combination on the.

keyboard selecting contacts, the new combination would be transferred to the keyboard selecting relays as soon as the lookout relay LOR and'the keyboard KBR are deenergized.

We will now consider the operation of translating the impulsescorresponding to a code combination into carrier oscillations for transmission to the distant station. The rei lay 2Q, it will be remembered, is normally energlzed and consequently maintains the grid circuit of the oscillating tube G closed through the condenser 39, so that the oscillator normally generates high frequency 0s cillations of the frequency assigned to the channel which oscillations are amplified b the amplifier TA and transmitted throug the sharply tuned circuit TF to. the common transmitting circuit TL. Oscillations of different frequencies from other transmitting channels may, at the same time, also be impressed upon the circuit TL. The oscillatlons appearing in this circuit are then transmitted to the artificial line MN, and to ated or the frequency of the oscillations is altered so that substantiall little or no current flows upon the line t rough the tuned ground, over the riglit hand front contact and V ircuit TF with the result that the receivmg distributor. at the distant station is released in a manner which will become apadditional closed circuit impulse. For each' closed circuit impulse a series of high frequency oscillations are generated by the oscillater G and after being amplified are transmitted over the main line ML to the distant station in a manner already described.

The last impulse of each group of seven is always a closed circuit impulse so that in the particular case hereindescribed the relay 20 remains continuously energized during the sixth and seventh impulses and high frequency oscillations from the oscillator G are transmitted to the distant station so long as the last impulse continues, which will, of course, be until the sending distributor is released for the transmission of the next code combination.

In order to understandt-he receiving operations taking place 'at the distant station in response to the transmission of high frequency oscillation in the manner just described, the operation of the apparatus associated with the receiving channel illustrated in Figure 2 will be considered. Let it be assumed that the same code combination as that already described is to be transmitted from the distant station. Normally high frequency oscillations of the frequency corresponding to the tuned circuit RF will be received from the line ML in the common receiving circuit- RL, which circuit may at the same time also be receiving high frequency oscillations corresponding to other channels. The frequency corresponding to the particular channel illustrated will be transmitted through the tuned circuit RF and amplified by the vacuum tube arrangements RA and RA and then rectified or detected by the I tube D, so that a direct current flows in the output circuit of the tube D having a value sufiicient to maintain the receiving relay 21 energized.

In response to the starting impulse, the oscillations corresponding to the receiving channel illustrated will cease to be trans mitted over the line ML so that the relay 21 is deenergized. A circuit is thereby completedflfrom ground,'over the back contact of relay 21, through the winding of the start relay STR, over the start segment S of the distributor, brush arm 40 and segment 41 of the distributor, to battery. The start relay STR is locked up over its lower front contact and at its upper front contact completes the circuit of the start magnet SM. The latter withdraws the releasing pawl 42 from the brush arm 40, releasing the brush which, upon passing from the start segment S, unlocks the start relay STR' which in turn causes the deenergization of the start magnet SM' so that the pawl 42 is again in position to engage the brush arin 40 at the-completion of its revolution.

The brush arm'40'of the receiving distributor RD now passes over the first segment of the outer ring of the distributor at an instant coinciding with the transmission of the first selecting impulse originating at the distant station which, in the case under consideration, is a closed circuit impulse. During this period, therefore, high frequency oscillations will be t-ransmitted'over the line ML and through the tuned circuit RF to the translating apparatus, whereby the relay 21 is energized. A momentary circuit is, therefore,completed from ground, over the 35 front. contact of relay 21, over conductor 43, segment 44, brush arm 40 and first segment of theouter ring of the distributor to the first selecting relaly (not shown) of the receiving printer R v The brush arm 40 next rotates over the second segment of the outer ring of the distributor RD. At this moment an open circuit condition occurs and consequently no high frequency oscillations pass through the tuned circuit RF The relay 21 is, there fore, deenergized and no circuit is completed over the second segment of the outerring of the distributor to the corresponding selecting relay of the printer. i

As the brush'arm 40 passes over the third and fourth segments of the distributor, closed circuit and open circuit intervals occur re spectively so that for the third segment a' selecting relay of the receiving printer is 5 circuit is therefore completed over the front contact of'said relay and over the fifth segment of the distributor for the fifth selecting relay'of the receiving printer. As the brush 12o arm passes over the sixth segment, a circuit is completed from battery, over segment 41, brush arm 40, sixth segment of the outer ring of the distributor and over the conductor P .to the receiving printer to print the combination set up on the selecting relays of the printer in a well understood manner.

The brush arm now passes to the segmen S of thedistributor and comes to rest in engagement S of the distributor and comes to 139 in Figure 2. Finally it should be noted that due to the conjugate relation of the common transmitting circuit TL and the common receiving circuit RL the two sets of transmls sions in opposite directions may take place simultaneously.

In order to further increase the number of signalling channels which may be operated over a 511'! 1c line, the arrangement illustrated in igure 3 may be provided. The high frequency portion of the apparatus in this figure is identical with that illustrated in Figure 2 and need not be further 'described. Each high frequency channel has associated with it, however, instead of a smgle printer, a multiplex printing arrangement so that four printers may be operated over each channel. For this purpose transmitting distributor TD and receiving distributor RD of the continuously rotating type are provided, a transmitting distributor being associated with each transmitting channel, and a receiving distributor being associated with each receiving-channel. Similar' distributors rotating in synchronism therewith will be provided for the corresponding channels at the distant station. The transmitting distributor TD includes twenty segments on its outer rin divided into four groups of five each. The rst group is associated with a tape transmitter T. schematically illustrated as comprising a set of five contacts adapted to be connected either to battery or to ground. The other three groups of five segments each are connected to corresponding transmitters T T and T The receivin distributor RD is illustrated as comprising twenty live segments in its outer ring, separated by a corresponding number of dead segments. The live segments are divided into four groups of five each, the first group of five being connected to the se lecting re ays of a receiving printer schematically indicated at R.. The remaining three groups of .five segments each are connected to receiving printers R R and R But five segments are provided for each sending and receiving unit since, owing to the fact that the distributors at the distant stations are continuously operated in synchronism, no starting and stopping impulses are necessary and consequently only the five code impulses it determining the character need be transmitted. I

The transmitting distributor TD is provided with an inner ring 44 connected to the transmitting relay 20 so that as the brush arm 45 passes over the segments of the'outer ring,

impulses may be tfansmitted to said relay.

Similarl the receiving distributor RD 15 provide with an inner ri the front contact of the receiving relay 21, so that the impulses received by said relay may be transmitted to the various segments of the outer ring as the brush arm 47 rotates.

Further details of the apparatus ma now be understood from a description of t e operation:

Assumin that the transmitter T, is operated to shi its first, third-and fifth contacts to their alternate positions, as the distributor arm 45 rotates over the corresponding first, third and fifth se ents of the outer ring of the distributor, t e circuit of the relay 20 will be-closed, but the circuit of said relay will be opened as the brush arm passes over the second and fourth segments. The transmittingl relay 20 is thereufion operated to close t e grld circuit of' t e oscillator G through the condenser 48 each time said relay is energized, thereb causing the oscillator to generate correspon groups of oscillations 46 connected to of the frequenc corres ndin to this ar- 1 y g P ticular channel. These gh frequency oscillations are amplified b the amplifier TA and transmitted throug the sharply tuned circuit TF to the common receiving circuit TL. Oscillations of frequencies corresponding to other transmitting channels may at the same time be impressed upon the circuit TL for transmission over the main line lllL to the distant station. Y

The receiving operation tion may be understood from a consideration of the receiving operation at the station illustrated in response to the transmission of .a similar code combination from the distant station. Assuming that at the distant station the transmitter corresponding to the receiving printed RA transmits closed circuit impulse to its transmitting relay while its brush armis passed over its first, third and fifth segments, three successions of high frequency at the distant Sta oscillations will be received from the main line ML and transmitted through the sharply tuned circuit RF At the same time oscillations ofother frequencies maybe received from the main line ML and transmitted to the other receiving channels. The three successions or'g'roups of oscillations transmitted through the tuned circuit RF are a'm lified by the tubes RA, and RA and recti ed or nels or the number of printer channels as passes over the third and fifth segments, simiopen circuit condition, while the brush arm of the distant distributor was passing over the second and fourth segments. a I

The first of these received pulses occurs just as the brush 47 is passing over the first receiving segment of the first group of five segments of the outer ring of the distributor RD. A circuit is therefore completed from ground, over the front contact of relay 21, inner ring 46, brush arm 47 and first segment of the outer ring to-the first selecting relay of the receiving printer R,,. As the brush 47 lar circuits are completed for the third and fifth selecting relays, so that the receiving printer R prints the character corresponding to the actuation ot the transmitter at the distant station. As the brush arm passes over the next group of five receiving segments, relay 21 will receive impulses corresponding to a combination set up onanother transmitter at the distant station and similar operations take place for each quadrant of the distributor.

It will, therefore, be seen that for each transmit-ting channel, four printer transmitters may be provided, while for each receivin channel a corresponding number of printers may be provided. The particular number assigned to each high frequency channel' may, of course, be variable, four being illustrated simply because it conforms to-the common printer practice. It will also be understood that high frequency transmission may take place for all channels simultaneouslfy in both directions Without interference. so t at for the case illustrated sixteen separate transmissions may take place over the line ML in one direction and a corresponding number of transmissions take place over the line in opposite direction. By increasing either the number of high frequency chansigned to each highfrcquency channel, the total number may be further increased;

It will also be obvious that while the invention has been disclosed as embodied in cer tain forms Which are considered desirable from a practical standpoint, the general principles herein disclosed may be embodied in many other organizations widely different from those illustrated, without departing from the spirit of the invention as defined in the following claims:

What is claimed is:

1. In a'signaling system, a transmission circuit adapted to transmit carrier oscillations, Baudot code determining means, a vacuum-tube translating device associated with saidtransmission circuit, means to impress a carrier frequency of constant amplitude'upon the circuit of said vacuum tube translating device, a transmitting distributor for transmitting to said vacuum tube translatmg device Baudot-code combinations of impulses determined by said code determin: ing means, means whereby the impulses thus transmitted operate through the circuit of said vacuum tube translating device to determine the transmission to said'transmission circuit of carrier oscillations modified in accordance with said code combinations, a vacuum tube detector associated with said transmission circuit for translating the car'- rier oscillations transmitted over said circuit into code combinations of impulses corresponding to the original Baudot code com-' bination, printing means responsive to Bandot code combinations to print characters, and a receiving distributor for distributing the detected impulses to said printing means.

2. In a signaling system, a' transmission circuit adapted to transmit carrier oscillations, a plurality of carrier channels extending over said circuit, a vacuum tube translating device associated with each channel, means whereby carrier oscillations of different frequencies may be supplied to the circuits of the vacuum tube translating devices of the several channels, Baudot code determining means for each channel, a transmitting distributor for each channel for transmitting to the vacuum tube translating device of each channel Baudot code combinations of impulses determined by said code-determining means, said Baudot code combinations of impulses controlling through said vacuum tube translating device the transmission of carrier oscillations modified in a ac cordance with the code combinations to said transmission circuit, means to separate'carrier oscillations transmitted over said transmission circuit and having different fre quencies corresponding to different transmitting channels into corresponding receiving channels, a vacuum tube detector associated with each receiving channel to translate the oscillations selected into that channel into Baudot code combinations of impulses corresponding to the original Baudot code combinations set up in the corresponding transmitting channel, printing means associated with each receiving channel to print characters corresponding to the detected Baudot combinations, and receiving distributors for each channel for distributing to the printing means the Baudot code combnations detected by the detector of that channel.

3. In a signaling system, a transmission circuit adapted to transmit carrier oscillations, means to generate a carrier frequency of constant amplitude, translating means for. cdntrolling said carrier frequency of constant amplitude in accordance with low frequency impulses, means to impressthe con-' trolled oscillations upon said transmission circuit, a plurality of Baudot code determining means, and a transmitting distributor for successively transmitting to said translating means the several independent code combi- I nations of impulses individually determined by each of said code determining means, said impulses controlling said carrier oscillations through said translating means.

4. In a signaling system, a transmission circuit adapted to transmit carrier oscilla-v tions, means to generate a carrier frequency of constant amplitude, translating means for controlling said carrier frequency of constant amplitude in accordance with low frequency impulses, means to impress the translated oscillations upon said transmission circuit, a plurality of Baudot code determining means, a transmitting distributor for successively transmitting to said translatin means the several independent code com inations of impulses individually determined by each of said code determining means, said impulses controlling said carrier oscillations through said translating means, means to translate high frequency oscillations transmitted over said transmission circuit into impulses corresponding to the original code combinations, a plurality of printing means for printing characters corresponding to code combinations, and a receiving distributor for successively distributing code combinations of the translated impulses to the corresponding printing means.

5. In a signaling system, a transmission circuit adapted to transmit carrier oscillations, a plurality of carrier channels extending over said transmission circuit, means to generate a carrier frequency of constant amplitude for each. channel, translating means associated with each channel for controlling the carrier oscillations of the frequency asv signed to the channel'in accordance with low frequency impulses, means' to impress the controlled oscillations from the several channels upon said transmission circuit, a plurality of Baudot code determining means for 'eaclrchannel, and a transmitting distributor for successively transmitting to said translating means the several independent code combinations' of impulses individually determined by each of the code determining means associated witheach channel, said impulses Q controlling said carrier oscillations through said translating means.

In a signaling system, a transmission circuit adapted to transmit carrier oscillations,

, a plurality of carrier channels extending over the carrierv several inde n'dent code combinations of' eral printing means of each channel code combinations of translated impulses corresponding to the several printing means.

7 In a system of high frequency telegraphy, a transmitter comprising an electron tube oscillator,'a grid control circuit therefor,

means for variably modifying said grid circuit through each of a definite number of successive definite time intervals for each character signal to thereby transmit energy in corresponding combinations of impulses and means for receiving said impulses, means for amplifyin said impulses, a relay actuated by said impulses and a type printer controlled by said relay whereby said impulses select particular characters and cause said characters to be printed.

8. In a system of high frequency telegraphy, a transmitter comprising an electron tube oscillator for generating continuous oscillations, means for variabl modifying the transmission of said oscillations during each of a definite number of successive time intervals for each signal to thereby produce a characteristic succession of impulses, means for receiving said impulses, means for amplitying said impulses and a selective relay operated by said impulses and adapted to control a circuit to an automatic printer having means controlled by said combinations of impulses for selecting characters and causing same to be printed.

9. In a system of high frequency telegraphy, the combination at atransmitter of an electron tube oscillator and selectively controlling means therefor arranged to place said oscillator, for each character signal transmitted, in either one of two conditions during each of a definite number of successive time intervals of definite duration, to therebyproduce a characteristically timed succession of impulses for each character signal; at a receiver, an electron tube apparatus for receiving and amplifyin the transmitted signals, -an electron tube. re ay responsive to the amplified impulses of the signals, a magnet controlled by said relay, and a printer mechanism selectively controlled by said magnet for printing characters in accordance with the signals.

10. In a system of high frequency telegraphy, means to generate continuous oscillations, a control circuit therefor, means for variably modifying said control circuit through each of a definite number of successive definite time intervals for each character signal to thereby transmit energy in corresponding combinations of impulses, means for receiving said impulses, means for amplifying said impulses, a relay actuated by said impulses and a type printer controlled by said relay whereby said impulses select particular characters and cause said characters to be printed.

11. In a system of high frequency telegraphy means for generating continuous oscillations, means for variably modifying the transmission of said oscillations during each of a definite number of successive time intervals for each signal to thereby, produce a characteristic succession of impulses, means for receiving said impulses, means for amplifying said im ulses and a selective relay operated by sai pulses and adapted to control a circuit to an automatic printer having means controlled by said combinations of impulses for selecting characters and causing same to be printed.

12. In a signaling system, a transmission circuit adapted to transmit high frequency oscillations, printer code determining means, a modulator associated with said transmission circuit, means to impress high frequency oscillations of constant amplitude upon said modulator, a transmittin distributor for transmitting to said modu ator printer code combinations of impulses determined by said code determining means, means whereby the impulses thus transmitted operate through the circuit of said modulator to determine the transmission to said transmission circuit of high frequency oscillations modified in accordance with said codes combinations, a receiving circuit for receiving such oscillations,

means associated with said receivingcircuit for translating received high frequencies 0scillations into code combinations of impulses corresponding. to the original printer code combination, printin means responsive to said printer code com inations to rint characters and a receiving distributor or distributing the translated impulses to said printing means.

In testimony whereof, we have signed our names to this specification this 27th day of August 1919.

HERMAN A'. AFFEL.

BAXTER P. HAMILTON. 

